The development of sensors that can detect hazardous analytes selectively and accurately, particularly sulfur based irritants, is quite essential. The infinite-conjugation in cyclic conducting polymers make them highly sensitive to toxic analytes. We implemented B3LYP-D3/6–311 + G (d, p) level to explore the sensing mechanism of cyclic tetrapyrrole (CTPy) for reliable detection of carbonyl sulfide, carbon disulfide, hydrogen sulfide sulfur monoxide, sulfur dioxide and sulfur trioxide using the DFT practice. The interaction energies, ${\mathrm{E}}_{\mathit{int}}$ ranges from –25.6 to –89.2 kJ mol⁻¹ for sulfur gases over CTPy. Charge transfer interactions in complexes are predicted using natural bond orbital (NBO) and charge decomposition (CDA) analysis. The reduced density gradient (RDG) method supports hydrogen bonding and dispersion interactions in the complexes. The decrease in HOMO-LUMO energy gaps, as well as the red shifting of ${\mathrm{\lambda }}_{\mathit{max}}$ in UV–Visible spectra, demonstrate sensitivity of CTPy towards sulfur gases. The improved conductivity of complexes is owing to production of numerous energy levels in occupied and virtual orbitals closer to the Fermi level in DOS spectra. Furthermore, PDOS spectra reveal that CTPy is chiefly contribute to energy of HOMO. The recent findings show CTPy has a significant sensitivity to sulfur irritants. We hope that the above findings and their implications will give valuable suggestions for an experimentalist in designing extremely sensitive hazardous analyte sensors employing CTPy.

开发能够选择性且准确地检测有害分析物（尤其是硫基刺激物）的传感器非常重要。环状导电聚合物中的无限共轭使它们对有毒分析物高度敏感。我们实施了 B3LYP-D3/6–311 + G (d, p) 水平来探索环四吡咯 (CTPy) 的传感机制，以可靠检测硫化羰、二硫化碳、硫化氢一氧化硫、二氧化硫和三氧化硫DFT练习。相互作用的能量，${\mathrm{乙}}_{\mathit{整数}}$对于超过 CTPy 的硫气体，范围为 –25.6 至 –89.2 kJ mol ^-1。使用自然键轨道 (NBO) 和电荷分解 (CDA) 分析预测复合物中的电荷转移相互作用。减少的密度梯度 (RDG) 方法支持复合物中的氢键和分散相互作用。HOMO-LUMO 能隙的减少，以及红移${\mathrm{\lambda }}_{\mathit{最大限度}}$在紫外-可见光谱中，证明了 CTPy 对含硫气体的敏感性。复合物电导率的提高是由于 在 DOS 光谱中更接近费米能级的占据轨道和虚拟轨道中产生了许多能级。此外，PDOS 光谱显示 CTPy 主要贡献于 HOMO 的能量。 最近的研究结果表明 CTPy 对硫刺激物具有显着的敏感性。我们希望上述发现及其意义能够为实验者在使用 CTPy 设计极其敏感的危险分析物传感器时提供有价值的建议。